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Hydrogel Composite Membranes Incorporating Iron Oxide Nanoparticles as Topographical Designers for Controlled Heteronucleation of Proteins

Year: 2018

Journal: Cryst. Growth Des., Volume 18, JUN, page 3317–3327

Authors: Salehi, Shabnam Majidi; Manju, Ana C.; Belviso, Benny D.; Portugal, Carla A. M.; Coelhoso, Isabel M.; Mirabelli, Valentina; Fontananova, Enrica; Caliandro, Rocco; Crespo, Joao G.; Curcio, Efrem; Di Profio, Gianluca

Organizations: Education, Audiovisual and Culture Executive Agency (EACEA) through the programme Erasmus Mundus Doctorate in Membrane Engineering EUDIME [FPA2011-0014]; Associated Laboratory for Sustainable Chemistry-Clean Processes and Technologies LAQV; FCT/MCTES [UID/QUI/50006/2013]; ERDF [POCI-01-0145-FEDER-007265]; Fundacio para a Ciencia e a Tecnologia, FCT (Portugal)

In this study, we exploited the possibility of tuning physical-chemical properties of hydrogel composite membranes (HCMs) surfaces, by using iron oxide nano particles (NPs) as topographical designers, with the aim of examining the effect of surface topography and wettability on the heterogeneous nucleation of protein crystals. On the basis of roughness and contact angle measurements, it was found that surface structural characteristics, in addition to chemical interactions between the surface and protein molecules, have influence on the heterogeneous nucleation of lysozyme and thermolysin crystals to different extents. We demonstrated that increasing the amount of NPs incorporated in the hydrogel matrix promotes protein nucleation to a higher extent, potentially due to the increase of local solute concentration, arising from the enhanced wetting tendency in the Wenzel regime, and physical confinement at rougher hydrophilic surfaces. An extensive crystallographic analysis suggested the tendency of the growing crystals to incorporate hydrogel materials, which allows inducement of protein conformational states slightly different from those covered by standard crystallization methods. Protein flexibility can be thus sampled by changing the amount of NPs in the HCMs, with negligible influence on the quantity and quality of X-ray diffraction data.